SOLUTION: The length of a rectangle is five times its width. If the area of the rectangle is 320cm^2 , find its perimeter

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Question 509236: The length of a rectangle is five times its width.
If the area of the rectangle is 320cm^2 , find its perimeter




Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The formula for perimeter is:
+P+=+2W+%2B+2L+
The formula for area is:
+A+=+L%2AW+
given:
+A+=+320+ cm2
(1)+L+=+5W+
----------
(2) +320+=+L%2AW+
(2) +L+=+320%2FW+
Substitute (2) into (1)
+320%2FW+=+5W+
+320+=+5W%5E2+
+W%5E2+=+64+
+W+=+8+
and, since
+L+=+5W+
+L+=+40+
The length is 40 cm and the width is 8 cm
so, the perimeter is
+P+=+2W+%2B+2L+
+P+=+2%2A8+%2B+2%2A40+
+P+=+16+%2B+80+
+P+=+96+ cm